Many hypersomniacs suffer from narcolepsy, for which the primary symptom is excessive daytime sleepiness.
许多嗜睡症患者患有发作性睡病,其主要症状是白天过度嗜睡。
英语百科
Excessive daytime sleepiness
Excessive daytime sleepiness (EDS) is characterized by persistent sleepiness and often a general lack of energy, even during the day after apparently adequate or even prolonged nighttime sleep. EDS can be considered as a broad condition encompassing several sleep disorders where increased sleep is a symptom, or as a symptom of another underlying disorder like narcolepsy, sleep apnea or a circadian rhythm disorder.